Method of forming doped film

Abstract

A doped film forming method comprising, the steps of preparing gas source for supplying a film forming gas into the process tube, gas source for supplying doping gases, in which a dope is included, into the process tube, a dry pump for exhausting the process tube, and an apparatus for burning a not-reacted element in waste gas, arranging a plurality of substrates in the process tube in such a way that they are separated from their adjacent ones by a certain interval, exhausting the process tube to keep it reduced in pressure, heating the substrates in the process tube to a temperature range of 500°-600° C., controlling amounts of the doping and film forming gases, while exhausting the process tube, at the ratio of the amount of the film forming gas to the amount of the doping gases being in the range of 1 to 1.625×10 -3 to 2.125×10 -3 , and causing the doping and film forming gases to be reacted with the substrates.

What is claimed is: 
     
       1. A method of forming a doped film on a substrate, said doped film having improved uniformity of thickness on said substrate and an improved homogeneity of dopant in said film, which comprises: a) assembling a process tube, means for supplying a film forming gas into the process tube, means for supplying doping gas into the process tube, pump means for exhausting the process tube, and means for burning any unreacted elements in a waste gas from the method;   b) arranging a plurality of substrates in the process tube;   c) exhausting the process tube to maintain reduced pressure;   d) heating the plurality of substrates in the process tube to a temperature range of 500°-600° C.;   e) introducing the doping and filming forming gases into the process tube, while exhausting the process tube, a flow rate ratio of said dopant gas to said film forming gas ranging between 1.625×10 -3  to 2.125×10 -3 , and a flow amount of the film forming gas of 48 to 807 SCCM/m 2  being supplied to a unit surface area of each substrate, said film forming gas being SiH 4  and said doping gas comprising PH 3  in an amount of 1±0.1% by volume in an inert gas; and   f) decomposing said film forming gas and said doping gas into Si components and P components by heat, and uniformly adsorbing the Si components and the P components on an entire surface of each of the substrates by hindering the P components from being deposited on a peripheral portion at each of the substrates earlier than the Si components, thereby improving uniformity of thickness of inter-films formed on the substrates, uniformity of thickness of a film formed on the substrate, uniformity of impurity concentrations of inter-films formed on the substrates, and uniformity of impurity concentration of a film formed on the substrate.   
     
     
       2. The doped film forming method according to claim 1, wherein 300-5000 SCCM of the SiH 4  gas is supplied to 170 silicon wafers whose diameters are 6 inches each. 
     
     
       3. The doped film forming method according to claim 1, wherein the speed at which the polysilicon film including the dope is formed is 30 Å/min or more. 
     
     
       4. The doped film forming method according to claim 1, wherein the internal pressure of the process tube is set within the range of 0.4-0.6 torr, when the gases are supplied to the process tube. 
     
     
       5. The doped film forming method according to claim 1, further comprising the steps of preparing the burning means and burning unreacted gases included in the gas exhausted from the process tube by means of the burning means. 
     
     
       6. The doped film forming method according to claim 1, wherein the wafers are rotated while the gases are being supplied to the process tube. 
     
     
       7. The doped film forming method according to claim 1, wherein the gases are introduced from a lower portion of the process tube. 
     
     
       8. The doped film forming method of claim 1, wherein the dispersion of film thickness is within a range of ±1% upon film forming and within a range of ±2 to 3.5% after annealing and a P concentration of the formed film is within a range of 5 to 6×10 20  particles/cm 3 .